The UK's Climate Change Act (CCA) has been functioning for five years. This report provides an overview of its influence so far, with a specific focus on the power sector, and including both key domestic processes and interaction with EU climate policy, particularly the EU emissions trading system. As regards domestic processes, the CCA has led to a more long-term perspective in policy.making. This can be noticed for instance in the case of Electricity Market Reform. With regard to interaction with the EU, this has been quite smooth so far, with the CCA targets using EU policy as focal points. However, as the CCA has emissions reductions targets extending up to 2027 and the EU so far only to 2020, ensuring a good match here is a key challenge ahead.